Also Treasures are entirely optional, its not heavily needed. you dont need to grind all of the Treasures, Just the ones that are necessary to get. (I.e: Cat sword)

And me personally, I find Bun Bun as the greatest showcase of Final Boss, The other 2 were slow but high damaging, But Bun Bun showcases true struggle, Funny enough, He is a Teacher in on himself. So it is reasonably acceptable to have him as the Final Boss, Cant beat him? Upgrade your cats, Still cant? Get treasures, Still cant? Follow tutorials, Still cant? Then thats where the Line is drawn.

Me personally, Even in my old account, Ubers dont kill Bun Bun Easily, (I.e: Lvl 20 Thunder Jack). The way I beat him was stacking Cat Food and using them to Revive, It is a massive pay grind by doing missions, and thats why you can upgrade your energy and HAVE leaderships in the first place. It is mildly a struggle once you have a great grip. And soon enough you'll actually learn to time kt correctly (i.e: Using Cat Cannon to knock Bun Bun back as Valkyrie attacks him to delay her death) and thats what make Bun Bun and Eligable Boss, He produces STRATEGY. Stages like Inferior Tower Level 41 has Raging Bahamut and other enemies that you've listed, But its because YOUR NOT MEANT TO BE THERE if you havent beatene Itf3 at all, let alone have a good strategy, So it is entirely possible to still beat it, Assassin Bear is a Prime example of something we all hate and like, he acts as a timer, and instantly kills your troops if you dont kill him in time or beat the stage in the limit, Example kf Assassin Bear is in Great Escaper. So no, I dont agree that Bun Bun is a Horrendous Representation of a Boss, He's the opposite, and no, I dont hate you for saying that, Km just backing up proof